I have written a script which is supposed to loop through all the rasters in a folder and perform a slope analysis on each raster and save the results in another folder.

I keep getting the following error:

< type 'exceptions.RuntimeError'>: ERROR 000875: Output raster: C:\Slope_Outputs\burd_25m_dem_slope's workspace is an invalid output workspace.

Here's my code:

class LicenseError(Exception):

# Set desktop license used to ArcView
import arcview
import arcpy
from arcpy import env

    if arcpy.CheckExtension("Spatial") == "Available":
        # Raise a custom exception
        raise LicenseError

except LicenseError:
    arcpy.AddMessage("Spatial Analyst license is unavailable")
    print arcpy.GetMessages(2)

from arcpy.sa import *

originLocation = arcpy.GetParameterAsText(0)
slopeMeasurement = arcpy.GetParameterAsText(1)
destinationLocation = arcpy.GetParameterAsText(2)

arcpy.env.workspace = originLocation

rasterList = arcpy.ListRasters("*")

for raster in rasterList:
    finalDestination = destinationLocation+"\\"+raster+"_slope"
    outSlope=arcpy.sa.Slope(raster, slopeMeasurement)

I'm not really sure why I'm getting this error.

Any ideas?

4 Answers 4


I have found on this page that the maximum raster name length is 13 characters. I have modified my code to take the first 7 characters of the input raster name and add "_slope" at the end of it.

This works for now, but I think I will modify my code to write to a different file format instead of ESRI GRID or possibly a geodatabase instead.

  • someone told me before that, the file name length should be 8, 11 or 13. He was not sure. 11 length worked for me. So, I told you to keep the name length less or equal 11. thanks for sharing the link :)
    – Emi
    Jan 24, 2013 at 2:35
  • 3
    How about adding "_slope.tif" at the end? GeoTIFFs are fantastic, with no funny name length limitations.
    – Mike T
    Jan 24, 2013 at 3:37

try changing the workspace name to this C:\Slope_Outputs\burd_25m_dem_slopes. I think the problem might be that you are using unsupported characters in your workspace name. Maybe this post for ESRI will be helpful

  • There are no unsupported characters in the workspace name. The apostrophe after 'slope' was added by ArcGIS in displaying the error.
    – Fezter
    Jan 24, 2013 at 0:32

I am not sure about it. But Try those:

  1. Try change the drive.
  2. Try keep the raster name length less than or equal 11.

Perhaps the "\" is causing problems. Try the following:

import os # add this in with your other imports at top of code
finalDestination = destinationLocation + os.sep + raster + "_slope"

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